I own both Winchester LR primers AND Winchester LR MAG primers. Both do exist.Winchester just makes one large rifle primer. Since Winchester Olin used a lot of ball powders they designed a large rifle primer that ignited the ball powders reliably. I think it may matter what part of the country you are in. I noticed several years ago that the 1000yd shooters out west used a lot of magnum primers. Myself and many others here in the southeast used non magnum for the 300 Ackley. I tested many primers and the non magnum Fed GMM gave me the best results for primers readily available. RWS and the old Russian Primers were "cold" compared to most. They could deliver some amazingly low SD. Testing is the answer. Whatever works I do not question.